The Peace Sentinel's Escort troops often carried the M10 into battle with them, while escorting various vehicles. Big Boss and his mercenary group, the Militaires Sans Frontières, later procured design specs relating to the M10 at El Cenegal's swamp while attempting to track Amanda Valenciano Libre's Sandinista National Liberation Front towards the Bananal Fruta de Oro in an attempt to find out if nukes did indeed exist. They later added a suppressor onto it. During a holdup exercise at Bananal Fruita de Oro's Sorting Shed, the MSF also procured design specs relating to a variant of the M10 that utilized a Bullet Jacket and put it into development.

Post-Peace Walker

By 1975, the MAC-10/M10 was removed from the use of the United States military.

Behind the scenes

Metal Gear Solid: Portable Ops

M10 icon in Portable Ops.

"Compact and light, this American-made light submachine carries a 32-round magazine of powerful 9x19mm ammo, firing at a rate of over 1,000 rounds per minute. This excessively fast firing rate has a negative impact on accuracy; but in the hands of a seasoned marksman, it can deliver massive firepower in a matter of seconds.Can be equipped with a suppressor."

Metal Gear Solid: Peace Walker

"A miniature light submachine gun developed for Special Forces use, notable for its extremely compact, highly portable design. The M10's extremely high rate of fire allows the user to pelt the target with a barrage of well-placed shots, giving it impressive stopping power. This power comes at the expense of accuracy, however, as the gun's small size is ill-balanced against its high recoil. It takes a great deal of practice to bring out this submachine gun's full capabilities; the best approach is to keep using it until you are thoroughly familiar with how it handles. (Rank 2) Equipped with a limited-use suppressor. The suppressor will eventually wear out, so use it prudently. (Rank 3) This model is fitted with a barrel jacket, slightly increasing the weight and shifting the center of gravity forward. The effect is to reduce muzzle jump, improving the gun's firing accuracy."